Photoelectric apparatus for detecting surface defects in glassware



I5 Sheets-Sheet 1 Sept. 13, 1949. E. R. OWENS PHOTOELECTRIC APP FOR DETECTING SURFACE DEFECTS GLASSWA RI ARATUS IN Filed April 26, 1945 Wm M H UNITED STAT ES PATENT OFFICE rno'ronmc'raro APPARATUS non na'rno'r- ING SURFACE armors 1N GLASSWARE Elliott It. Owens, Whittier, Calm, assignor to tw6:is Illinois Glass Company, a corporation Application April as, 1945 Serial No. 590,309

I 3 Claims. (Cl- 88-l4) My invention relates to apparatus for inspectdetecting apparatus is mounted on a supporting bottles, jars, and other containers or articles frame comprising a platform It carried on posts made of glass or like material, for the purpose of H and 2. Vertical rods (3 secured at their detecting crizzles, checks, fire cracks, tears, and lower ends on the platform I ll carry an upper other defects in or near the surface of the article. 5 platform l4 on which is mounted an electric The invention in the form herein illustrated is motor I 5. The motor drives a. horizontal light particularly adapted for use in detecting surface chopper disk It attached to the lower end of irregularities or defects in the finishes or sealthe motor shaft II. The purpose and operation ing surfaces of the articles under test. of the chopper disk are set forth hereinafter.

Containers such as glass bottles and jars are The article 26 to be inspected, herein shown extensively used at the present time for sealing as a glass Jar. is placed on a pad 2| in the form products under a partial vacuum, and the reof a circular disk. The pad is mounted for roexacting. Containers made of glass are inherentlowered for bringing the Jar into and out of 1y subject to surface defects such as minute position or t e te ts e Ja i lifted for cracks or fissures, plunger marks, seeds, surface the testing operation, it is center d by a frustolines, blisters, and the like, many of which are conical stationary block 24 which enters the not easily detected by the usual methods of inmouth of the Jar. Conical rolls 25 are positioned spection. Any such defect in the sealing surand arranged to contact the rim 26 of the Jar face is apt to permit a slow leakage after the con- 20 and hold the jar centered as it rotates.

tainer is sealed. An object of the present inven- The Dad 2| with h J r h r on s rotated tion is to provide detecting means operable autocontinuously by an electric motor (not shown) that light is reflected from the surface of any The light source of the detecting apparatus is crack, check, crizzle or similar surface defect 30 herein shown as an electrical lamp 30, preand directed to a photoelectric cell or tube. The focused and mounted on a supporting plate 3| latter operates to produce an electrical impulse extending upward from the platform M. A which is amplified. and serves to operate indicatcollecting reflector 32 above the lamp reflects ing means. light downward and directs it to a condensing Other objects of the invention willappear herelens 33. The lens is attached to the upper end inafter. of a metal tube 34 which is adjustable up and Referring to the accompanying drawings which down within a bearing sleeve 35 formed on a illustrate an apparatus embodying the present plate 36 supported on the platform l0. Teleinvention in a form particularly adapted for inscopically connected with thetube 34 for vertical specting the sealing surfaces or finishes of jars, and rotary adjustment therein, is a tube 31 sebottles, or other containers: cured in adjusted position by a set screw 38. Fig. 1 is a part-sectional elevation of the ap- Attached to the lower end of the tube 31 is a box paratus with parts broken away. 39 in which is mounted a prism 40 of glass, or

Fig. 2 is a section at the line 2-2 on Fig. 1. the like. The prism is formed with an inclined Fig. 3 is a fragmentary part-sectional elevasurface 4! coated with silver or other reflecting tion on a larger scale showing particularly the material to provide a reflecting surface.

condensing lens, reflectors and phototube, the A second reflecting prism 42 is mounted in a section being at the line 3-3 on Fig. 4. box 43 attached to the lowerend of a tube 44. Fig. 4 is a section, on a still larger scale, at the As shown in Fig. 3, the prisms 40 and 42 are 1ine4-4 on Fig. 3. at the same level and at about the same height Fig. 5 is a fragmentary part-sectional plan as the rim 26 of the container. .As shown in Fig. showing the light source and the light chopper 4, the light beam 56 is projected horizontally disk, from the reflecting surface ii and strikes the Fig. 6 is a wiring diagram of the apparatus. surface 66 under test at an angle of substantially Referring particularly to Figs. 1 and 2, the 45 degrees to the direction of movement of said surface. The testing zone or area of the surface 56, namely, the area at which light strikes said surface, is preferably a short distance within the focal point of the beam of light. Any surface defect 51 passing through the testing zone is thus brought within the concentrated light beam and reflects light toward the reflecting prism 42 which is positioned to receive light rays reflected from the surface defect 51 at an angle of about 90 degrees to the incident rays. The prism 42 has a reflecting surface 42 which extends in a vertical plane and is arranged diagonally with respect to the incident light rays for projecting them toward a third prism 45 also mounted in the box 43. The prism 45 has a reflecting surface 45 inclined at an angle of 45 degrees for reflecting the light vertically through the tube 44. The prisms and their reflecting surfaces may be all of the same materials as above described in reference to the prism 40.

The tube 44 is adjustable up and down in a split the plate 36 and is clamped in adjusted position by a screw 41. the upper end of the tube 44 is a frame for supporting a photoelectric cell 50, said frame comprising a base and an upright member 52. The cell is enclosed in a casing 54.

The photocell 56 or electric eye may be of conventional construction, either a high vacuum photoemissive tube or a tube of the gas-filled type.

While the pad 2! is in lowered position, a jar 26 is placed thereon and then lifted to the testing position (Figs. 1 and 3) and rotated while held in centered position by the rolls 25. Light is directed downward from the lamp 36 and reflector 32 and passes through the condensing lens 33 by which the light rays are focused or converged to form a beam of light which enters the prism 40 and is reflected horizontally from the surface 4|. This horizontal beam of light 55 (Fig. 4) is directed toward the upper surface 56 or finish of the horizontally-rotating jar, said surface being formed on the rim 26 of the jar.

Any defect 51 in the sealing surface 56, such as a crizzle, check, tear, minute fissure or break in the skin or surface of the glass, as it passes through the light beam 55, will present a, reflecting surface by which a portion of the light beam is reflected toward the prism 42. entering the prism 4'2 is reflected from the surface 42 horizontally toward the prism 45, the surface 45 of which directs the light vertically upward through the tube 44 to the photocell 50.

It is found that substantially any defect 51 in the surface of the glass such as a crack or crizzle whether extending across the surface at right angles to the direction of movement or at some other angle or irregularly, will reflect a portion of the beam of light and direct it against the prism 42 so that a flash of light is transmitted to the photocell and operates to produce therein an electrical impulse.

It will be observed that if the defect 51 is in the nature of a crack or crevice below the level of the surface 56, the beam of light 55 must penetrate the glass before it contacts the defect and is reflected therefrom. Light of various wave lengths may be used provided they come within the spectral transmission range of the glass which is being tested.

1 have found that with some types of testing apparatus and in testing certain lines of ware, it is advisable to provide some means either electrical, such as an oscillator, or mechanical, for

The light causing the photocell to give an alternating current signal adaptable to the work in hand and which favllitates the amplification of the electric impulse. In the apparatus herein disclosed, the light chopper disk l6 used for this purpose, is positioned to extend across the path of the light rays between the lamp, 36 and the lens "3 and is provided with an annular 'series' of openings which as the disk rotates, cross the path of the light beam. The disk may be made of aluminum and is rotated at a high speed. If the motor i5 is driven, for example, at or approximately at 3450 R. P. M., a chopper disk with fifteen holes will produce about 862 flashes of light per second or 431 cycles in an A. C. circuit. This gives satisfactory results and is found to be practical because it is near one of the standard frequencies for electronic equipment and simplifies the combination of the photoemissive cell with standard amplifier elements.

Referring to Fig. 6, there is provided amplifying means by which a current impulse from the phototube 56 is amplified sufficiently to operate signaling devices and switches or relays in controlling circuts for any suitable mechanism for rejecting defective ware or segregating it from the articles which pass the test. The amplifying mechanism includes an amplifier tube 62 which may be a vacuum tube or triode of standard construction, and a gas-filled tube 63. The anode 59 of the phototube is connected through a wire to the positive terminal i? of the battery B, the negative terminal of which is grounded. A resistor R is connected between the cathode 56 and ground wire 66. When the phototube is energized by a flash of light projected thereon as before described, the conductivity is increased with an increase in flow of current through the circuit including wire 65, battery B and resistor R The voltage balance across the condenser 61 is thus upset causing the condenser to start a flow of current through the resistor R ground wire 66 and a resistor R This current flow causes the bias voltage of the grid 68 to be less negative with respect to the cathode 69. This results in an instantaneous increase in the flow of current through the plate circuit of the tube 62, said circuit including the plate Ill, a resistor R and batteries B, B. The current in this plate circuit is thus amplified to a sumcient degree to operate the tube 63, the latter in turn serving to operate a signal and relay presently to be described.

The change or increase in plate current of tube 62 causes an unbalance of the potential across a condenser 1|. This results in a current flow from one side of the condenser through a resistor R to ground wire 66 and through batteries 13,13 and a resistor R to the other side of the condenser. One side of the condenser 1| is connected to the control grid 12 of the tube 63. This grid has a bias sufficiently negative in respect to its cathode 13 to prevent it from passing current from the cathode to the anode or plate 14. However, the condenser 1| in releasing electrical energy and starting a current flow as above described for restoring equilibrium, causes the grid 12 to become less negative with respect to its cathode 13, to a degree which permits a current flow from the cathode to the anode and on through the plate circuit. This circuit extends from the plate 14 through an indicator 15, such as a neon indicator lamp, a relay magnet coil 16, a switch 11, wire 18, batteries B, B and B to ground wire 66 and thence through a resistor R and to the cathode 13. The gas-filled tube 63 when once fired or set into operation as above described, operates on direct current and con- 7 tinues to pass current until the anode circuit is opened regardless of the grid bias voltage so that it keeps the relay coil I9 energized until the switch 11 is opened.

The switch 11 is opened after each testing operation is completed and is closed before the next test commences.

The relay magnet 16 operates to close a switch 80 in an ejector circuit connected across the mains 8i and 82 connected to a source of current supply. Said circuit includes a magnet coil 83 forming part of an ejector mechanism, and a switch 84 which is closed by a cam 85. The ejecting mechanism may be of any approved form such, for example, as that disclosed in my Patent No. 2,338,868, January 11, 1944, Gauging apparatus, and may be operated in a similar manner. Ejecting mechanism such as disclosed in the Fedorchak Patent No. 2,371,748, March 20, 1945, Article handling apparatus, may be employed if desired.

Modifications may spirit and scope of my I claim:

be resorted to within the invention.

1. Apparatus for testing the annular sealing surface of a glass container such as a jar or bottle, said apparatus comprising a support .for the article rotatable about a vertical axis for thereby rotating a said article and causing the surface under test to traverse a testing zone, an electric lamp, means for directing light rays downward from said lamp. a vertical tube, a condensing lens at the upper end thereof, said lens being in the path of said downwardly directed light rays for converging said rays as they pass downward through the tube, a reflecting prism at the lower end of said tube comprising a reflecting surface inclined at an angle to deflect the light beam horizontally toward the testing zone, a second prism displaced from the path of light rays reflected from the said surface of the container passing through said zone, said second prism having a refleeting surface positioned to receive light reflected in a different direction by a surface defect passing through said zone, a third prism having a reflecting surface in the path of the reflected light from said second prism and inclined in a direction to reflect the light upwardly, a tube extending upwardly from said third prism through which the light is directed, a photoelectric cell above said last mentioned tube in position to be energized by said upwardly directed light, and indicating means controlled by said photoelectric cell.

The combination of a support for a glass jar or other glass article having an annular sealing surface, means for rotating the support and an article thereon about the vertical axis of said surface and thereby causing the surface to move in a horizontal path and to traverse a testing zone, a vertical tube mounted at one side of said path and extending upwardly thereabove, a condensing lens on the upper end of said tube, an electric lamp mounted above said lens and arranged to direct a light beam downward through the lens and cause it to be condensed, a reflecting prism at the lower end of said tube having an, inclined reflecting surface arranged to direct the beam of light across the surface under test at said testing zone, a second reflecting prism positioned to receive horizontal rays of light from said beam reflected from the surface of a crack, crizzle, or other defect in the said sealing surface, a photoelectric cell, means for directing light reflected from said second prism to said cell, and indicating means controlled by said cell.

3. The combination of a support for a glass jar or other glass article having an annular sealing surface, means for rotating the support and an article thereon about the vertical axis of said surface and thereby causing the surface to move in a horizontal path and to traverse a testing zone, a vertical tube mounted at one side of said path and extending upwardly thereabove, a condensing lens on the upper end of said tube, an electric lamp mounted above said lens and arranged to direct a light beam downward through the lens and cause it to be condensed thereby, a reflecting prism at the lower end of said tube having an inclined reflecting surface arranged to direct the beam of light across the surface under test at said testing zone. a second prism having a reflecting surface positioned in the path of light rays reflected from the surface of a defect in said sealing surface under test, said reflecting surfaces being at substantially the same height and intersected by a horizontal plane at the level of the said surface under test, a light sensitive cell, and means for causing the light rays reflected from said second prism to impinge on said cell.

- ELLIOTT R. OWENS.

REFERENCES man The following references are of record in the flle of this patent:

UNITED STATES PATENTS Number Name Date 1,640,567 Firestone Aug. 30, 1927 1,925,814 Nicolson Sept. 5, 1933 1,934,187 Glasgow et al. Nov. 7, 1933 1,979,722 Zworykin Nov. 6, 1934 2,068,567 Simonton July is, 1935 2,065,713 Knobel et al. Dec. 29, 36 2,219,572 Everett Oct. 29, 1940 2,313,218 Brace et al. Mar. 9, 1943 2,318,856 Hoifman May 11, 1943 2,335,686 Mercur Nov. 30, 1943 FOREIGN PATENTS Number Country Date 381,335 Great Britain Oct. 6, 1932 649,180 Germany Aug. 17, 1937 

